The Study On The Recovery Of Valuable Metals From Spent Mobile Phone By High-temperature Smelting Based On The Slag System Of Al₂O₃-FeO_x-SiO₂-CaO

The new types of e-waste, such as mobile phone, is an important secondary resource. Compared with the traditional e-waste, they are rich in a variety of high-value rare and precious metals, with higher recycling value. But due to its small size, the complex structure and components, the traditional e-waste "crushing--sorting--smelting" process will lead to not only low physical separation efficiency but also much dispersion and loss of precious metals. In this study, taking spent mobile phone PCBs and undismantled mobile phone as research object, respectively, a high temperature smelting method using an aluminum oxide enriched slag system Al2O3-FeOx-SiO2-CaO is proposed to recovering the valuable metals. Based on thermodynamic calculation of Factsage software, the liquidus projection and iso-viscosity curves were drawn, and the calculation or analysis about thermodynamic behavior of the reaction of main elements in the smelting process is done, the reasonable temperature and slag composition region were selected. Based onAl2O3-FeOx-SiO2-CaOslag system, a series of smelting study were focuses on the key smelting. The major conclusions can be summarized as follows:(1) For the smelting process Fe is a critical element, and the iron content in alloy is an important instruction of oxygen partial pressure.(2) Based on the calculation and analysis, suitable smelting conditions are selected, namely oxygen partial pressure of 10-10~10-8atm,1300?~1450?,7wt% CaO,10~15wt% Al2O3, Fe/SiO2 ratio of 0.8~1.0.(3) The lab smelting experiments about spent mobile phone PCBs showed that the reasonable condition, namely smelting temperature 1350?,7wt%CaO,10wt%Al2O3, Fe/SiO2 ratio of 1.0,insulation for 30 min,and the recovery rates of Cu, Ni, Sn, Au, Ag were 98.49%,97.33%,95.44%,99.69%,98.89%,respectively.(4)The reasonable condition can be used for smelting of old keyboard mobile phone, and the recovery rates of Cu, Ni, Sn, Au, Ag were 98.49%,97.33%,95.44%,99.69%,98.89%, respectively. But it cannot achieve the goal for waste smartphone like the old keyboard mobile phone, and the effect of Cr2O3 should be considered.